Among the following, which one is the **least** water-efficient crop?

Gives a quantitative crop water requirement for sugarcane in mm (1500–2500 mm), a direct measure of depth of water needed over the growing season.

Convert mm to liters per unit area (1 mm = 1 L/m²) and then divide by typical yield (kg/m² or kg/ha from external sources) to estimate L/kg.

Provides a general physiological rule: about 400–500 litres of water are required to produce one kilo of plant dry matter.

Combine this dry-matter L/kg with data on the dry-matter fraction of harvested sugarcane (requires an external typical % dry matter) to infer irrigation L/kg of harvested produce.

States sugarcane is among crops with ‘very high’ water needs, implying its L/kg will be large compared with cereals.

Use this qualitative ranking to compare any L/kg estimate for sugarcane against known L/kg values for other crops (from external sources) to judge plausibility.

Notes sugarcane is predominantly cultivated in irrigated tracts and accounts for substantial production on limited area, implying intensive water input per area.

Combine the high area-based irrigation intensity with regional typical yields (external) to estimate L/kg and assess whether a given statement is consistent with irrigated cultivation.

Lists sugarcane explicitly as an example of an irrigated crop, reinforcing that irrigation-dominated water accounting applies to it.

Use irrigation-crop classification to justify using seasonal irrigation-depth figures (from evidence 1) rather than relying solely on rainfall for L/kg calculations.

Gives a general conversion-style rule: about 400–500 litres of water are necessary to produce one kilo of plant dry matter.

A student could combine this per‑kg‑dry‑matter figure with typical harvest index (seed vs total dry matter) and sunflower yield figures (from external sources) to estimate litres per kg of sunflower seed.

Provides crop-wise water requirements expressed as depth (mm) for several crops and notes WUE concepts and typical WUE percentages.

A student can convert mm irrigation requirement to cubic metres per hectare (1 mm = 10 m3/ha = 10,000 litres/ha), then divide by typical sunflower yield (kg/ha from external data) to get litres/kg.

States that high‑yielding varieties use less water per unit of output because they mature faster and give higher yield per area.

A student could adjust a base litres/kg estimate for sunflower upward or downward depending on whether the cultivar is traditional or HYV, using known yield differences.

Describes drip irrigation as a method that reduces wetted area and increases efficiency for row crops and tree crops by supplying water close to roots.

A student could use reported efficiency gains from micro‑irrigation to scale down litres/kg estimates obtained under surface irrigation to approximate drip‑irrigated sunflower values.

Gives pearl millet's (bajra) annual rainfall requirement (about 30–50 cm) and explicitly states it is highly drought- and heat-tolerant with the highest water-use efficiency among crops.

A student can combine this low rainfall requirement with a water-to-depth conversion (mm or cm to liters per hectare) and crop yield to estimate liters per kg.

Provides an average grain yield for bajra (~650 kg per hectare), a necessary denominator to convert water applied per hectare into liters per kg of produce.

Use the yield (kg/ha) together with an estimated total water depth (from rainfall requirement or irrigation needs) to compute liters per kg.

Defines Water-Use Efficiency (WUE) concept and lists water requirements for several crops in millimetres (mm), showing that crop water needs are commonly expressed as depth of water over area.

Apply the same mm-to-volume approach used for listed crops to bajra (using its cm/mm requirement from snippet 3) and then divide by yield (snippet 5) to get L/kg.

Describes dryland farming thresholds (annual rainfall <75 cm) and the role of irrigation as supplementary water; places bajra's rainfall needs (30–50 cm) in context of low-water regimes.

Use the dryland context to argue that bajra typically needs less supplemental irrigation than high-water crops, lowering its liters/kg compared with crops needing >75 cm.

Explains that micro/drip irrigation increases transport efficiency and reduces water input per plant (example systems delivering precise small flows).

A student could factor likely irrigation method (rainfed vs. micro-irrigation) to adjust estimated liters/kg downward if efficient irrigation is assumed.

Gives a general physiological rule: about 400–500 litres of water are necessary for production of one kilo of plant dry matter.

A student could use this as a baseline, estimate the proportion of harvested produce that is dry matter for pigeon pea, and thereby approximate litres per kg of harvested grain.

Describes pigeon pea's agronomic behaviour: it grows across wide climates, tolerates heavy rainfall and irrigation but cannot tolerate standing water, implying moderate (not extremely high) water needs compared with rice/sugarcane.

Combine this crop-specific tolerance with maps/knowledge of typical yields to infer pigeon pea’s likely water use intensity relative to high-water crops.

Provides crop water-requirement values (mm) for several crops, illustrating how mm-depth data are used to compare water needs across crops.

A student can apply the conversion 1 mm over 1 ha = 10,000 litres to convert mm-based requirements into litres per hectare, then divide by typical pigeon pea yield (kg/ha from external sources) to get litres/kg.

States that certain crops (rice, sugarcane, jute) have very high water requirements and implies irrigation necessity; useful as comparative anchors when judging pigeon pea’s water efficiency.

Use these high-water crops as reference points (from snippet 1 and 3) so a student can judge whether pigeon pea is likely to lie above or below those litres/kg benchmarks once yield and water-use data are combined.

Explains the distinction between protective and productive irrigation and that irrigated lands have higher inputs per area—context for interpreting per-kg water use depending on irrigation strategy.

A student could consider whether pigeon pea is typically grown under protective or productive irrigation in a region (using external agronomic data) and adjust litres/kg estimates accordingly.